The instant invention is related generally to vibratory conveyors, and more specifically to the art of controlling the application of vibratory force to the material-conveying member of a conveying system so as to alter the motion thereof to adjust the speed and/or direction of conveyance for different materials having varying physical properties.
Vibratory conveyors have long since been utilized in manufacturing plants for conveying all types of various goods having different weights, sizes and other physical characteristics. Through the use of such conveyors, it has become apparent that articles having different physical characteristics frequently convey better under different vibratory motions, and therefore require a different application of vibratory force to the material-conveying member to obtain the optimal conveyance speed of the material being conveyed. It is also desirable under certain circumstances to change the direction in which the material is conveyed.
Most conventional vibratory conveyors are of the type which "bounce" the conveyed goods along the path of conveyance on the material-conveying member of the conveyor system. Such conveyors of the conventional type generate a resultant vibratory force which is directed at an angle relative to the desired path of conveyance (angle of incidence), so that the material being conveyed is physically lifted from the material-conveying member and urged forwardly as a result of the vibratory force applied thereto. In order for such a conventional "bouncing" vibratory system to operate effectively, the vibratory force must be of a magnitude sufficient to overcome the weight of the material being conveyed, and must have a substantial vertical component. Such a vertical component of force is undesirable due to both the damaging vertical forces resultant on the building structure supporting the conveyor, and the product breakage which occurs when fragile products are bounced along the conveyor.
The need to convey various materials of differing weights and physical characteristics more effectively have lead to efforts in designing conveyor systems in which the direction of the application of vibratory force to the material-conveying member, and consequently the motion thereof, may be altered to accommodate such differing materials. For such conveyors of the conventional type, efforts have been made to change the angle of incidence of the resultant vibratory force in order to adjust the speed and/or direction of conveyance. For instance, as shown in U.S. Pat. No. 3,053,379, issued to Roder et al on Sep. 11, 1962, a conveyor system is provided with a pair of opposing counter-rotating eccentric weights which produce a resultant vibratory force along a centerline between such weights and through the center of gravity of the material-conveying member. Each eccentric weight is driven by a separate motor, and by reducing the power to one of such motors, the eccentric weight driven thereby is effectively pulled along by the rotational power of the first motor at a synchronous speed, but with the eccentric weight lagging in phase, thereby changing the angle of incidence of the resultant vibratory force applied to the material-conveying member.
By way of another example, as shown in U.S. Pat. No. 5,064,053, issued to Baker on Nov. 12, 1991, one of the rotating eccentric weights of the vibration-generating means may be mechanically altered in its angular position relative to the remaining rotating eccentric weights, thereby again causing a change in the angle of incidence of the resultant vibratory force, which may change the effective speed of conveyance, as well as the direction of conveyance, if desired.
More recently, however, because the "bouncing" nature of such conventional conveyors tends to damage the products conveyed thereby, and produce substantial noise and dust, product manufacturers have sought the use of conveyor systems of a different type which are substantially devoid of vibrational forces normal to the desired path of conveyance. Such conveyor systems, similar to a conventional SLIP-STICK conveyor, manufactured by Triple S Dynamics Inc., P.O. Box 11037, 1031 S. Haskell Avenue, Dallas, Tex. 75223, or similar to that shown in U.S. Pat. No. 5,131,525, issued to Musschoot on Jun. 21, 1992, operate on the theory of a slow-advance/quick return conveyor stroke, which conveys the product while advancing slowly, and causes the product to slip on the rapid return stroke by breaking the frictional engagement of the material with the material-conveying member. Conveyors of this type do not have the negative effects which are produced by the conventional "bouncing" type conveyor, since they employ motion which is substantially only parallel with the desired path of conveyance, and virtually eliminate all motion perpendicular (normal) thereto.
However, because the resulting conveyor stroke of such conveyors must remain devoid of components of force in a direction normal to the desired path of conveyance, the application of vibratory force to the material-conveying member cannot be changed by altering the angle of incidence of the resultant vibratory force, as done with conventional conveyors. To do so would destroy the intended function and mode of operation of such a conveyor system. Therefore, as shown in U.S. Pat. No. 5,131,525, the vibratory drive system of such conveyors are set such that the eccentric weights used for generating the resultant vibratory force are disposed in a fixed position relative to one another, thereby creating the desired slow-advance/quick return conveyor stroke which is substantially only in a direction parallel with the desired path of conveyance. No mechanical means is provided for adjusting the application of the resultant vibratory force to the material-conveying member, much less doing so without changing the direction of the resultant line of force produced thereby.
As can be seen from the above, there is a distinct need for a vibratory conveyor system which is capable of transmitting vibratory forces to the material-conveying member substantially only in a direction parallel with the desired path of conveyance, while providing means for adjusting the application of vibratory force to the material-conveying member, without changing the direction of the resultant line of vibratory force generated thereby. Providing such capability in a single vibratory conveyor system will enable the user thereof to easily and effectively change the motion of the material-conveying member to match the physical characteristics of the material being conveyed thereby, and to alter the speed and/or direction of conveyance, without destroying the intended function of the conveyor system by introducing undesirable components of force in a direction normal to the desired path of conveyance for the material.